A common practice in manufacturing insulation products from fibrous mineral material is coating the fibers with an organic binder, such a phenolic resin, and collecting the fibers in the form of a pack. The uncured pack is then passed through an oven through which flow high temperature gases to cure the organic binder on the fibers, thereby bonding the fibers together. Some curing systems for fibrous mineral material utilize heated plates which cure the binder by radiation and conduction. The plates can be adapted with hot air passageways for the passage of curing gases therethrough. Heated plates can also be used in pre-cure or post-cure processes in which the surface of the fibrous mineral material is passed in contact with the plate to provide a smooth surface on the product.
One of the problems associated with curing fibrous mineral material products with heated plates is that as the resinous binder material is heated it becomes sticky, and tends to gum up the curing apparatus. Prior to entering the curing apparatus the binder is generally maintained at a temperature below 100.degree. F. (38.degree. C.) at which temperature the binder is not sticky. Once the binder reaches a temperature above approximately 550.degree. F. (288.degree. C.), cure of the binder is effected, and the binder is not sticky. In the interim temperature range, from about 100.degree. F. (38.degree. C.) to about 550.degree. F. (288.degree. C.), however, the water is driven off the binder, causing the binder to become more viscous and sticky, resulting in fouling of the curing equipment. In an attempt to solve the above problem, the entrance plates positioned upstream from the heated curing elements are usually provided with passageways for water cooling fluid. Nevertheless, even though the use of water cooling maintains the binder in the less-than-sticky temperature range, below 100.degree. F. (38.degree. C.), as long as possible, the binder still must pass through the transition temperature range, 100.degree. F. (38.degree. C.) to 550.degree. F. (288.degree. C.), at which time the binder is sticky. This invention provides a solution to the problem of sticking binder during the curing process.